From a practical standpoint, the wiring of the human eye - a product of our evolutionary baggage - doesn't make a lot of sense. In vertebrates, photoreceptors are located behind the neurons in the back of the eye - resulting ...

A brighter ray of hope is on the horizon for the blind, as scientists improve electronic hardware that creates sight - making it possible, they predict, to read printed text, recognize faces and lead normal, independent lives.

(Medical Xpress) -- Two researchers at Weill Cornell Medical College have deciphered a mouse's retina's neural code and coupled this information to a novel prosthetic device to restore sight to blind mice. The researchers ...

(Medical Xpress)—Blind mice can see again, after Oxford University researchers transplanted developing cells into their eyes and found they could re-form the entire light-sensitive layer of the retina.

Researchers at the University of California, Berkeley, have developed an easier and more effective method for inserting genes into eye cells that could greatly expand gene therapy to help restore sight to ...

(Medical Xpress)—Vision – so crucial to human health and well-being – depends on job-sharing by just a few cell types, the rod cells and cone cells, in our retina. Botond Roska and his group have identified ...

The neural machinery underlying our olfactory sense continues to be an enigma for neuroscience. A recent review in Neuron seeks to expand traditional ideas about how neurons in the olfactory bulb might encode information about ...

(Medical Xpress)—Neurophysiologist like to think of neurons as communicating with spikes. If that were the whole story, it might be possible to imagine spike codes which could then be used to estimate the ...

A degenerative eye disease slowly robbed Roger Pontz of his vision. Diagnosed with retinitis pigmentosa as a teenager, Pontz has been almost completely blind for years. Now, thanks to a high-tech procedure ...

(Medical Xpress)—For UCLA bioengineering professor Wentai Liu, more than two decades of visionary research burst into the headlines last month when the FDA approved what it called "the first bionic eye for the blind." ...

Progressive degeneration of photoreceptors—the rods and cones of the eyes—causes blinding diseases such as retinitis pigmentosa and age-related macular degeneration. While there are currently no available ...

The time most of us spend looking at a screen has rapidly increased over the past decade. If we're not at work on the computer, we're likely to stay tuned into the online sphere via a smart phone or tablet. ...

Retina

The vertebrate retina is a light sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical events that ultimately trigger nerve impulses. These are sent to various visual centers of the brain through the fibers of the optic nerve.

In vertebrate embryonic development, the retina and the optic nerve originate as outgrowths of the developing brain, so the retina is considered part of the central nervous system (CNS).. It is the only part of the CNS that can be imaged non-invasively in the living organism.

The retina is a complex, layered structure with several layers of neurons interconnected by synapses. The only neurons that are directly sensitive to light are the photoreceptor cells. These are mainly of two types: the rods and cones. Rods function mainly in dim light and provide black-and-white vision, while cones support daytime vision and the perception of colour. A third, much rarer type of photoreceptor, the photosensitive ganglion cell, is important for reflexive responses to bright daylight.

Neural signals from the rods and cones undergo complex processing by other neurons of the retina. The output takes the form of action potentials in retinal ganglion cells whose axons form the optic nerve. Several important features of visual perception can be traced to the retinal encoding and processing of light.